317
FXUS63 KDVN 060520
AFDDVN

Area Forecast Discussion
National Weather Service Quad Cities IA IL
1220 AM CDT Wed Aug 6 2025

.KEY MESSAGES...

- There is a low chance (20-30%) of thunderstorms Wednesday
  afternoon through Wednesday night, mainly southwest of the
  Quad Cities. A few storms could produce gusty winds.

- Hot and humid weather returns to the area by the end of the
  week and weekend, with some reaching into the low 90s.

- An unsettled pattern returns Saturday night through Monday
  with higher chances for showers and storms (30-50%).

&&

.SHORT TERM /THROUGH THURSDAY/...
Issued at 130 PM CDT Tue Aug 5 2025

Current Conditions and Synoptic Overview: Water vapor and upper
air analysis continues to show several key features that will
come into play over the coming days. One such feature was the
shortwave trough moving east through Montana. Out ahead of the
trough was a mid level ridge extending from the southwest US up
into Iowa. The low levels continue to moisten across the area as
seen by the 12z KDVN sounding. A corridor of higher 850mb dews
and a cumulus field was also located across the southwest CWA.
However a prominent dry layer between 500-700mb is keeping a lid
on any vertical growth to the cumulus. Surface dewpoints
continue to creep up with middle to upper 60s now common. Temps
have also warmed into the lower 80s.

This afternoon through the overnight: Have continued the very
low pops (10-20%) across the southwest half of the area through
the afternoon and evening in case one or two showers are able to
develop however thinking that most if not all areas will remain
dry. The last few runs of the RRFS and HRRR output suggests
that some wildfire smoke may try to slide west again late
tonight through early Wednesday morning with the east winds.
This generally looks to affect areas of northwest Illinois and
far northeast Iowa and shouldnt be as significant as it was a
few days ago. Overnight, a MCS will develop across the Dakotas
on the nose of the low level jet. Latest HREF guidance takes
this MCS southeast into Minnesota and then a hard right turn
south, following corfidi vectors and the instability gradient
into western and central Iowa.

Wednesday: The MCS will likely be decaying/decreasing in the
morning hours across central Iowa and while most of it will stay
west of the area, we have put in some low pops (20-30%) across
the west in case a few showers/storms sneak in. Latest 12z
guidance then diverges with the potential for a MCV or outflow
that moves through during the afternoon. The 12Z HREF shows a
few CAMS with this solution however a number of CAMS are also
dry. With mean MU CAPE increasing, a few gusty winds could occur
if storms form. Currently the highest chances for this would be
southwest of the Quad Cities. We should at least see some cloud
debris during the day which would keep highs in the mid 80s.

Wednesday Night: Another low confidence scenario is showing
itself in the guidance as the low level jet develops again and
noses farther northeast into Iowa. Some CAMS, mainly the HRRR
are showing some additional redevelopment north and west of the
area that may sneak in. However the stronger lift does look to
stay north of the area. Again, confidence is low however if
storms do form then a few could produce gusty winds.

&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Issued at 130 PM CDT Tue Aug 5 2025

Thursday through Friday: Ensembles have now slightly increased
the potential for some energy to slide near or just north of the
area on Thursday. This could cause some additional rainfall with
10-20 percent Pops now north of I-80. Any higher clouds/precip
chances would also affect high temps from reaching near 90. Confidence
is low with additional updates likely. Confidence is higher that
Friday should largely remain hot, humid and dry as the mid level
heights rise and 850mb temps increase. Highs around 90 and
dewpoints in the low 70s would likely yield heat index values
approaching 100 degrees.

Saturday through Monday: Ensembles then show a strong signal for
a pattern change as shortwave energy moves across the northern
plains with a draped frontal boundary across the area. Precip
chances look low for the first part of Saturday however they now
increase into the 30 to 50 percent range at times from late
Saturday night through Sunday and then again on Monday. This
wet/unsettled pattern is supported by most of the ensemble
guidance therefore precip chances are likely to increase further
in future updates. This will impact high temps and could also
lower them in future updates. With the stronger forcing and
strong wind fields, there will be the potential for
organized/severe storms. There is a slight/weak overlapping
signal in the CIPS Analog severe probs and the Colorado State
University machine learning severe probs Saturday night through
Sunday.

&&

.AVIATION /06Z TAFS THROUGH 06Z THURSDAY/...
Issued at 1206 AM CDT Wed Aug 6 2025

VFR conditions will prevail through the TAF period. While some
are reporting lingering smoke, visibilities remain good
throughout. Thus, we are not expecting restrictions from that
at this time. Will monitor and update if necessary. Otherwise,
light easterly winds will become more southeasterly through the
night and daytime hours. No sig wx is expected at this time.

&&

.DVN WATCHES/WARNINGS/ADVISORIES...
IA...None.
IL...None.
MO...None.

&&

$$

SHORT TERM...NWS
LONG TERM...NWS
AVIATION...Gunkel